Winding tension control mechanism



Aug. 22, 1961 G. G. FORNES ET AL 2,996,870

WINDING TENSION CONTROL MECHANISM Filed June 1, 1960 4 Sheets-Sheet 1INVENTORS GASTON G. FORNES Y\II'OHN H. ROBINSON saw. m n

Aug. 22, 1961 G. G. FORNES ETAL WINDING TENSION CONTROL MECHANISM 4Sheets-Sheet 2 Filed June 1, 1960 INVENTQR S GASTON G. FORNES JOHN H.ROBINSON QWIM ATTORNE Aug. 22, 1961 ca. G. FORNES ET AL WINDING TENSIONCONTROL MECHANISM Filed June 1, 1960 4 Sheets-Sheet 3 IIII'I INVENTORSGASTON G. FORNES JOHN H. ROBINSON ATTORN EIYS Aug. 22, 1961 G. G. FORNESET AL wmnmc TENSION CONTROL MECHANISM 4 Sheets-Sheet 4 Filed June 1,1960 b lllll E:

INVENTORS GASTON G. FORNES BY JOHN H. ROBINSON ATTORNEYS United StatesPatent 2,996,870 WINDING TENSION CONTROL MECHANISM Gaston G. Fornes andJohn H. Robinson, Charlottesville,

Va., assignors to Institute of Textile Technology, Charlottesville, Va.,a corporation of Virginia Filed June 1, 1960, Ser. No. 33,211 11 Claims.(Cl. 57-95) This invention relates to the production of textile yarnsand, more particularly, to apparatus for providing improved tensioncontrol during winding of materials such as roving and the like toproduce packages having greater density and yardage.

Packages of textile roving are usually formed on roving frames or flyframes by winding roving on bobbins in successive closely wound layersso that the body of the fully wound bobbins is susbtantially cylindricalwith the ends tapered or in the shape of truncated cones. It isconventional practice to provide limited roving tension control duringwinding by decreasing the speed of rotation of the bobbins aftercompletion of each layer of roving. To do this, a gear arrangement isselected to limit roving tension, consistent with other factors, so thattension breaks are minimized. The gear arrangement can be changed onlywhen the frame is shut down.

With this arrangement, a generally constant tension is maintained andmaximum roving tension is not provided for each layer of roving. Rather,a relatively low tension is used at the inner layers in order thattension during winding of the outer layers will not cause breakagebefore the roving packages are completed. Full bobbins are thus woundwith a minimum of troublesome tension breaks but the roving packagesproduced have relatively low average density and low yardage.

As is well known, the conventional roving frame comprises a plurality ofdrafting rolls for attenuating each of a large number of ends of sliversso that the number of fibers in cross-section is reduced. The ends ofroving are then passed to another part of the frame which puts asubstantially uniform twist per unit length in the roving and then windseach end onto its own bobbin. The winding operation consists in layingthe end of a roving on a bobbin in successive layers, each layerconsisting of a plurality of relatively closely-spaced coils woundaround the bobbin.

Also, as is well known, the twisting and winding are both accomplishedby the differential rotation between the rotating bobbin and a so-calledflyer which rotates about the same axis as the bobbin. The roving is ledby the flyer to the bobbin and, in order that the coils will be laid onthe bobbin side by side and in successive layers, the roving frame isprovided with means which cause the bobbin to reciprocate axially withrespect to the flyer. Conventionally, a roving frame is also providedwith means which reduce the speed of rotation of the bobbin uponcompletion of each successive layer of roving. Thus the rate ofdisplacement between the flyer and the surface of the bobbin winding isprogressively reduced, as the circumference of roving layers increases.

The apparatus by which the speed of rotation of the bobbins is governedis called the cone drive. A first rotatable cone which has decreasingdiameter over its length is arranged in the frame parallel to a secondrotatable cone which has increasing diameter over its length. A belt isarranged on the cones to transmit the rotating motion of the first coneto the second. Suitable gearing arrangements transmit the rotary motionof the second cone to the bobbin spindles. Upon completion of each.layer of roving on the spindles, the belt is moved in a directionparallel to the longitudinal axis of the cones so that the speed ofrotation of the second cone and consequently of the bobbin spindles isreduced! In a conventional roving frame a tumbler shaft is arranged soas to make a half revolution upon completion of each layer of roving. Bymeans'of a so-called tension gear train which is driven in successiveequal increments by the half-revolutions of the tumbler shaft, a rack islongitudinally displaced in successive equal increments. This rack isconnected to a belt shipper. Thus each time the tumbler shaft makes ahalf-revolution, upon completion of each layer of roving, thebelt-shipper moves the cone belt along the cone a certain distance. Thebelt .is moved along automatically the same distance each time.

The tension gear train mentioned above controls the length of the rackand belt shipper movements. In order to vary the length of the beltshipper movements it is necessary to change the tension gear ratio. Thisis done by substituting tension gears with different numbers of teeth.Such gears can be changed between doffs when the roving frame is shutdown.

It has been standard practice in the past to select a tension gear ratioso that full bobbins may be wound with a minimum of tension breaks. Thebobbin rotation as controlled by particular tension gears, is adjustedonly enough to keep outer layer tension from becoming excessive andinner layer tension is less than the maximum permitted by roving tensilestrength.

The winding of roving on a bobbin is affected by many factors. Some ofthese factors are humidity and temperature, package stability, and size,evenness, stretch and compressibility of the particular roving materialbeing used. Package stability problems relate to the degree of supportwhich outer layers receive from inner layers. Each layer that is woundis affected by the layers pre viously and subsequently wound. To providestability, it has been conventional practice in the past to make rovingpackages with tapered conical ends. In this way the end coils of thelayers of the wound bobbin are supported on the underlying layers.Otherwise, the end coils overrun and tangle so that the package must bediscarded or unwound with difiiculty.

Because roving frames are limited to Winding roving to a certain maximumdiameter on the bobbins, many attempts have been made to increasepackage yardage by simply winding the roving under greater tension. Itappeared that roving could be compressed to a greater degree leavingroom for more layers to be wound on each bobbin. However, to do this,and still maintain package stability, it was found that the taper angleat the end of the packages would have to be reduced. Taper anglereduction directly reduced package volume, contrary to the purpose ofWinding with greater tension, and results were of indifferent success.

Recently, apparatus has been developed to build roving packages by a newmethod which forms packages having convex, rather than straight, endtapers. The immediate benefits of this method are that packages havegreater volume, and with proper winding tension, the ends of thepackages can be made more stable. in conjunction with these developmentsfurther investigation has shown that significantly greater Windingtensions can be used in making roving packages with the new convex endtapers. All of these factors combine so that packages having muchgreater yardage may be formed.

The purpose of this invention is to provide automatically operated meansfor improved tension control during winding of packages of roving or thelike. With this inventi-on winding tension is highest during winding ofinitial layers on the bobbin and is decreased gradually as the packageincreases in diameter. As a result average winding tension and averagepackage density are increased and stable packages of increased yardageand weight can be produced.

In the present invention, a cam controlled mechanism is used to changethe effects of the tension gears on the movement of the belt shipper.The step-movements of the rack can be provided in the conventional equalincrements, or they can be provided in constantly increasing, decreasingor exponentially varying increments. All of these steps are camcontrolled with the particular variations in rack movement beingdependent upon the axial position and the profile of a particular cambeing used.

According to our invention a flat cam is mounted in the roving frame forrotation about an axis. Tension gears are still used but only to limit,in a general way, the range of control of bobbin rotating speed obtainedthrough use of the cam. The tension gears, which are conventionallydisplaced in successive equal rotational amounts upon completion of eachlayer of roving, are utilized to provide successisve, equal angulardisplacements of the fiat cam. Thus, the gear ratio provided by theselected tension gears serves only to determine the magnitude of therotational displacements of the cam.

A flexible link such as a cable or chain is adapted to be wound aroundthe profile surface of the cam as the cam is turned. The contour of thecamming surface and the axial position of the cam are readily arrangedso that the amount of cable wound on the cam increases with eachsuccessive displacement. Now, with one end of the flexible link attachedto the cam, as the cam is rotated through successive, equal angulardisplacements the other end of the link or cable will be longitudinallydisplaced in successive increasing increments. The other end is thenconnected in the frame to drive the belt-shipper, likewise throughsuccessive increasing longitudinal displacements, to provide controlled,varying tension at the bobbins.

An important feature of our invention is the provision for radialadjustment of the flat cam. This permits changing the position of thegeometric axis of the cam with respect to its axis of rotation. Byadjusting the offset distance between these two centers or axes, finecontrol is obtained over the relative magnitude of the successisvelyincreasing longitudinal displacements.

For explanation, it may be helpful to consider first the effects ofusing a circular camming surface. With a circle, of course, equal anglesbetween radii or equal chords subtend equal lengths of arc. Therefore,with the geometric center of a circular cam arranged coincident with thecenter of its drive shaft (i.e., axis of rotation), successive equalangular displacements of the cam would produce successive equallongitudinal displacements in a cable being wound on the circularsurface. With the outer end of such a cable attached to a belt-shipper,successive belt-shipper step movements would be of constant magnitude.In such an arrangement, the belt-shipper would be moved in the samefashion as heretofore with the standard tension gear connections.

By offsetting the center or geometric axis of the cam from the axis ofrotation, however, the amount of cable wound on the camming surfacewould change with each successive angular displacement of the cam. Thus,such a cable can be used to pull a belt-shipper in varying amounts aftercompletion of each successive layer of roving.

To use the offset arrangement described, tension gears are selected toprovide a low gear ratio. The cam is arranged for starting with thecable tangent at the point of minimum radius from the rotation axis.With each succeeding cam motion, an increasing amount of cable is woundon the camming surface. As a result, the effects at the belt-shipper,viz., increasingly greater longitudinal displacements, can be comparedto the effects which would occur if the tension gear ratio could beincreased after each layer of roving.

Various combinations of cam contour, cam offset and tension gears may beemployed to effect roving tension during winding. The important resultfrom any combination is that much closer tension control is afforded.Cams can be made to produce any particular variation in rack movementdesired. With a given cam, fine control in roving tension for particularmaterials, package shape, prevailing mill conditions, etc., can be madewith the offset center adjustments.

The apparatus of our invention is readily fabricated and installed.Minimum roving frame modifications are required for installation. Onceinstalled, the combinations and adjustments possible for control ofroving tension provide a wide range of settings to compensate for themany physical factors which affect winding operations.

Heretofore, a given set of cone pulleys designed for specific roving andmill conditions, could produce only approximate results in the manyotf-design situations in which roving frames must function for practicalmill operations. With our invention, the effects of poorly designed orconstructed cones can be accommodated.

With our invention, a single cam for the most part can be used forcontrol of winding tension under diverse operating conditions. But forparticular or extraordinary situations, it is a simple matter to provideand install a cam of a difierent size and contour. High startingtensions can be used and packages of greater average density and muchgreater weight can be produced.

Greater package density and weight means that the roving frames can berun longer between shutdowns for changing bobbins. Hence, feweroperators are required to attend a given number of spindles. Also, theeffects of greater package yardage permit greater economy at otherlocations in the textile industry. The machinery subsequently used totake the roving from the packages can also be kept running longerbetween shutdowns to replace empty bobbins with full ones.

These advantages are particularly timely and important now that otherrecent developments have shown the feasibility of better controlling thevolume of roving packages. With new machinery for winding packageshaving convexly curved ends, increased tension provides packages ofgreater stability.

However, increased tension for this application must be accompanied byimproved tension control in order that correct tension can be providedat each roving layer. This invention is particularly suited for meetingthis requirement.

These and other features of the invention are described in detail in thefollowing portion of the specifications. For clarity, reference will bemade to the accompanying drawings in which:

FIG. 1 shows the components which, in a conventional roving frame,provide control of bobbin rotating speed;

FIG. 2 shows a preferred embodiment of this invention installed for usewith the apparatus of FIG. 1;

FIG. 3 is an enlarged view of a portion of the invention showing detailsof the device used for adjusting cam ofi-set;

FIG. 4 is a side view of the offset adjustment device of FIG. 3;

FIG. 5 shows an alternative embodiment of the invention adapted foroperation in another conventional type of roving frame;

FIG. 6 is a plan view of the embodiment of FIG. 5; and

FIG. 7 is an elevation view showing further details of the embodimentaccording to FIG. 5.

Inasmuch as the construction and operation of conventional frames arewell known, it will not be necessary to describe the entire machine toillustrate the operation of apparatus according to the presentinvention. A typical roving frame 'is fully described and illustrated inHill: Cotton Drawing, Combing and Fly Frame Processes, published byInternational Text Book Company of Scranton, Pennsylvania. Accordingly,there will be described here only so much of a typical roving frame asis necessary to enable those skilled in the art to comprehend thedetailed features of a preferred embodiment of the apparatus.

In FIG. 1 a conventional builder mechanism is shown connected by a shaftand gears to rack 11. As is well known, the builder mechanism 10 ismounted on a part of a roving frame called the bobbin rail or bolsterrail which carries the bobbin rotating mechanism. The bobbin rail andall the mechanism mounted on it are driven up and down so that thebobbins on which roving is being wound are reciprocated axially withrespect to the flyers. The flyers rotate with respect to the bobbins toput a uniform twist per unit of length in the roving and then wind it onthe bobbin in successive layers, each of which layers consists ofclosely wound coils. Adjacent to the builder mechanism 10 there is atumbler shaft 12 suitably mounted for rotation about its axis on astationary part of the roving frame. A so-called builder dog, indicatedat 13, is affixed to the tumbler shaft 12. As is well known,co-operating action of the builder mechanism 10 and the builder dog 13initiates reversal of the direction of reciprocation of the bobbin railupon completion of each successive layer of roving on the bobbins. Thebuilder mechanism also controls the amplitude of bobbin railreciprooartions.

The tumbler shaft is also provided with a spring-loaded cammingmechanism 14 arranged to urge the tumbler shaft to rotate in acounter-clockwise direction as viewed from the bottom of FIG. 2, therebyensuring that one or the other of the arms, on the builder dog will bearon the builder 1th. The tumbler shaft 12 is also positively, butintermittently, driven by the bevel gear 15 affixed to the upper end ofshaft 12 and the bevel gear 16 affixed to the main drive shaft 17 of theroving frame. As is well known, the gear 15 is a sector gear havingteeth in two opposite sectors and having no teeth in the other twoopposite sectors. The gear 15 is so oriented on the tumbler shaft 12that when one or the other of the arms on the builder dog is in positionengaging builder 10, a smooth sector of the gear 15 is adjacent or underthe gear 16 on the main drive shaft so that there is no driving torquetransmitted to the tumbler shaft 12.

Now, as the builder mechanism 10 is driven upward or downward to the endof the stroke of the bobbin rail, the arm of the builder dog 13, inengagement with the builder 10, will overrun the end of the builder sothat there is no longer any resistance to the turning movement exertedon the tumbler shaft by the spring-loaded camming mechanism 14. Thismechanism then causes the tumbler shaft to turn enough to bring atoothed sector of gear 15 into engagement with gear 16, and the tumblershaft is positively and rapidly driven through nearly a half revolutionbefore the next toothless sector of gear 15 comes under gear 16. By thistime, however, the spring-loaded camming mechanism 14 is again incontrol of the tumbler shaft and causes the shaft to complete thehalf-revolution and bring the other arm of the builder dog to bear onthe builder 10.

Those who are acquainted with textile machinery know that the halfrevolutions of the tumbler shaft also actuate a mechanism whichdetermines the direction in which the bobbin nail is driven. A t thesame time that the arm of the builder dog 13 overruns the upper end ofthe builder 10 and the tumbler shaft 12 turns through a half revolution,the driving mechanism of the bobbin rail is reversed by conventionalmeans so that the bobbin rail is then driven upward. The upward travelwill continue until the other arm of the builder dog overruns the lowerend of builder 1t], whereupon the tumbler shaft will again be turned bycamming mechanism 14 and the gears 15 and 16. The bobbin rail will againbe driven downwardly. These changes in direction of the bobbin railtravel cause the bobbins on all the spindles of the roving frame to bedriven up and down with respect to their respective fiyers which areaxially stationary. Each time the bobbin rail changes its direction oftravel, a new layer of roving is Wound on each of the bobbins.

As has been previously discussed, upon completion of each successivelayer of roving wound on the bobbins, in a conventional roving frame,the speed of rotation of the bobbins is reduced in order that rovingtension during the next layer of roving will not be excessive. In theconventional roving frame, this is accomplished by moving belt 18 insuccessive equal steps longitudinal of belt cones 19 and 2d. The firstbelt cone 19 as shown is mounted for rotation on the main drive shaft 17of the roving frame. The second belt cone 2% is mounted for rotation ona shaft which is parallel to the main drive shaft 17 The second cone isdriven by the belt 18. R0- tation of the second cone 2% and its shaftprovides, through conventional apparatus, rotation of the bobbinspindles in the roving frame.

The two cones 19 and 20 are oppositely tapered. As shown, cone 19 hasdecreasing diameter over its length and cone 20, the bobbin drive cone,has increasing diameter over its length. When winding is started, thebelt 18 is placed at the large diameter end of cone 19. As the windingprogresses and upon completion of each layer of roving, the belt ismoved in steps longitudinally of the cones. As the belt is moved alongthe direction of decreasing diameter on cone 19, the speed of rotationof cone 20, and hence the speed of rotation of the bobbins in the rovingframe, is reduced. This action keeps roving tension from becomingexcessive as the diameter of the layers of roving on the bobbinsincreases.

As shown at 21, a fork-shaped member called the belt-shipper is used toprovide the step movements in the belt. The belt-shipper 21 is connectedto rack 11 for longitudinal displacement upon completion of each layerof roving. The rack and belt-shipper are conventionally driven throughsuccessive equal longitudinal displacements by a gear train which isactuated upon each half revolution of the tumbler shaft 12. This geartrain, commonly known as the tension gearing, comprises a worm gear 22',fixed to the tumbler shaft, and spur gears 23, 24, 2-5 and 25. The gear23, in engagement with the worm 22, is affixed to a shaft which iscommon to the gear 24. The latter gear engages gear 25 which is afiixedto a shaft which is common to the gear 26. The gear 26 engages the teethon the under side of rack 11.

The rack is mounted on suitable guides so that it may be movedlongitudinally. The magnitude of the rack displacements is controlled bythe gear ratio of the tension gear train. Tension gears 24 and 25, canbe provided in different sizes for changing this ratio. Substitution ofdifferent tension change gears can be done when the roving frame is shutdown, to change the magnitude of successive step movements of belt 18.

Merely to orient the reader, it is well to state here that the rack gear11 is also the driving element for a taper gear train which in turnprovides successive displacements in the builder mechanism 10 uponcompletion of each layer of roving. The purposes of this mechanism arenot directly relevant to this invention and need not be described indetail. It is sufficient to indicate that this mechanism provides forchanging the amplitude of reciprocation of the bobbins and of the bobbinrail as well as initiating the sequence of events which is started uponrevolution of the builder dog 13 after each layer of roving iscompleted.

A tension gear and belt-shipper mechanism of the type shown in FIG. 1can, in general, provide a constant value of tension throughout windingof the roving. A tension gear ratio is established While the rovingframe is shut down. This ratio cannot thereafter be changed during thewinding operation. As a result, the tension control, provided bysuccessive equal displacements of belt 18 is approximate at best. Thetension gear ratio selected provides for relatively low tension duringwinding of the initial layers on the bobbin. The principal achievementis that roving tension is kept below a maximum, limited largely byroving tensile strength, so that full packages of roving may be woundwithout excessive tension breaks. The packages produced have low averagedensity, non-uniform density, and low total weight and yardage.

According to the preferred embodiment of our invention shown in FIG. 2,the rack 11 is disconnected from the belt shipper 21 and arranged in theroving frame so as not to interfere with belt shipper movements. Thetension gear arrangements for displacing the rack, in successive equallongitudinal increments, are generally the same as before. However,instead of driving the belt shipper, the rack is now used to drive aflat cam 27 as shown in FIG. 2, through successive equal angulardisplacements. Cam 27 is mounted on a shaft 28 for rotation about anaxis. A wheel gear 29 which engages the rack, is also mounted on camshaft 28.

As shown in FIG. 2, a rack extension 30 is arranged to engage the wheelgear 29 to drive the cam 27 through successive equal angulardisplacements upon each successive half revolution of the tumbler shaft12. Cam 27 is held in place on its shaft by a cam center adjustmentassembly shown at 31, details of which are shown most clearly in FIGS. 3and 4. A cam follower such as a flexible cable, tape or chain isconnected from the edge of cam 27 to the belt shipper 21 to providelongitudinal movement of the belt shipper whenever the cam is angularlydisplaced. In the embodiment of FIG. 2, a cable 32 is connected betweenthe cam edge and the belt shipper.

A tension linkage completes the arrangement. The linkage comprises acounterweight 33 suspended on a cable from, the belt shipper 21 so as toexert a force which opposes the force exerted by cam follower cable 32.Counterweight 33 is necessary to keep the belt shipper positively inplace between cam movements and to prevent overruns when the belt 18 isdisplaced in response to rotation of cam 27.

Now, with the one end of cable 32 attached to the edge 34 of cam 27, asthe cam is rotated the cable is wound on the cam. As successive amountsof cable are wound on the periphery of the cam, the other end of thecable 32 is longitudinally displaced in successive increments. With theother end of the cable attached to the belt shipper 21, the belt 18 willbe displaced in successive step-movements for control of bobbin rotatingspee For explanation, we will first describe the effects with a cam inwhich edge 34 comprises a circular arc camming surface. Of course, withsuch a camming surface, equal angles between successive radii from thecenter of the cam subtend equal lengths of arc. Therefore by mounting acircular arc type cam with its center or geometric axis coincident withthe axis of rotation of shaft 28, equal lengths of cable 32 will bewound on the camming surface edge 34 upon successive equal angulardisplacements of the cam. This action produces successive, equalstepmovements at belt shipper 21, analagous to the conventional actionprovided by the apparatus of FIG. 1.

By using the cam center adjustment assembly 31 of the invention, the camcenter or geometric axis of the cam can be off-set from the axis ofrotation. With the cam axis off-set, radii from the axis of rotation tothe camming surface will be unequal. By off-setting along the camdiameter which connects opposite ends of a semi-circular cammingsurface, the radii, from the rotation axis to the camming surface, willincrease from a minimum value in one direction along the describeddiameter to a maximum value along the other diameter direction.

As shown in FIG. 2, an off-set semi-circular cam is arranged with thecable 32 attached to the top of the cam tangent to camming surface 34 atthe point of intercept by the minimum radius. The maximum radius thusintercepts camming surface 34 at the bottom of the cam, or at the pointof last contact between the cam and the cable. As the cam is rotated inthe clockwise direction, in successive equal angular increments,successively increasing lengths of cable 32 will be wound on cammingsurface edge 34.

As a result belt shipper step movements will be of successively greatermagnitude. The speed of rotation of the drive cone 19 and hence of thebobbin spindles are automatically adjusted upon completion of each layerof roving to provide a reduced tension for winding of the succeedinglayer.

With the cam center adjustment assembly 31, much greater tension controlselectivity, than can be obtained through sole use of conventional beltcones and tension gears, is afforded. Changing off-set distance orsubstituting a cam of different profile, or both, is readily achievedwhen winding conditions are changed. The alternative is modification orsubstitution of belt cones which is not practical because in production,winding and mill conditions are changed frequently.

To build packages of increased density and yardage requires continuousstep-adjustments in roving tension during winding. Tension control whichcan be achieved by using the apparatus of our invention provides forhese adjustments and permits use of maximum roving tension consistentwith roving tensile strength and package stability, for each layer ofroving.

For operation with the offset center arrangement, tension gears 24 and25 which will provide a low tension gear ratio are selected. This ratiodetermines the magnitude of successive cam displacements. As increasingamounts of cable and are wound on the camming surface at each successiveequal angular displacement of the cam, the belt shipper will bedisplaced by successively increasing increments. The magnitude of theseincrements depends upon the profile of the particular cam being used,that is, the contour of a particular curved camming surface, and theamount of offset distance between the geometric axis of the cam and theaxis of rotation.

With our invention, much more precise tension control is provided. Theresulting action can be compared to the effects which would be achievedif the tension gears of the conventional mechanism of FIG. 1 could bechanged to provide successively greater gear ratios after completion ofeach layer of roving. But, as explained, in the conventional method, thetension gear ratio can be changed only when the roving frame is shutdown and during conventional operation all belt shipper step movementsare of constant magnitude.

The cam center adjustment assembly 31 is shown in detail in FIGS. 3 and4. An oblong slot 35, milled in the cam along the diameter connectingopposite ends of the camming surface edge 34, is provided to permitradial movement of the cam 27 with respect to its shaft 28. A collar 36is mounted on the shaft 28 for rotation with the same and is held inplace on the shaft by a suitable spline, key or lock screw arrangement.A cam slide 37 is positioned over the center of the cam 27 and over theslot 35. The cam slide and cam are held on the shaft by bolts 38 whichextend through both cam slide 37 and slot 35 into threaded holes incollar 36. The cam slide also has two oblong guide slots 39, arrangedparallel to slot 35. Slide 37 and cam 27 are held in radial alignment bybolts or studs 40 which extend through guide slots 39 into the cam. Aslide flange 41, and a cam flange 42 are also mounted on the slide 37and the cam 27 respectively to accommodate drive screw 43. Drive screw43 is arranged in flanges 41 and 42, parallel to the above-mentioneddiameter which connects opposite ends of the camming surface edge 34.

As shown, the lower end of the drive screw 43 is turned into andtightened in a threaded aperture in slide flange 41. A thumb nut 44 isarranged at the top of cam flange 42 with a hollow shaft projectingthrough an aperture in cam flange 42. The upper end of drive screw 43projects through the hollow shaft 45 and the -ing frame for the nextrun. gears are thrown out of mesh and the drive cone 20 is thumb nut 44.Drive screw 43 and the inner wall of hollow shaft 45 are threaded sothat when thumb nut 44 is turned, the drive screw and hence the camslide 37 can be displaced along the longitudinal directions of the screw43.

'It is advantageous to provide position indicator means in the camcenter adjustment assembly 31. For this purpose a graduated scale 46shown on the cam in FIG. 3, position marks 47 on top of thumb nut 44 anda pointer 48 supported on the cam flange 42 are provided. With the scaleand position marks provided, an operator experienced in the use of thecam apparatus of this invention can readily establish a predeterminedamount of cam offset. With this apparatus the cams used in thisinvention are made radially adjustable and very fine adjustments intension control can be made.

At the end of a doff it is necessary to reset the rov- To do this, thetension raised to clear the drive belt. The rack and belt shipper aremoved to the left to a position such as that indicated in FIG. 2 withthe flexible link or cable 32 being unwound from the camming surfaceedge 34. Counterweight 33 pulls the belt and belt shipper to the left sothat the belt is placed in its starting position at the left end ofcones 19 and 20..

Wheel gear 29 as shown in FIG. 2 is conveniently made a sector gear,since it is of suflicient diameter so that it does not make a completerevolution during a given winding operation on the roving frame. Havinga sector with no teeth, gear 29 thereby provides its own stops or limitsand thus the starting and terminal positions of the cam are readilycontrolled.

We have found that use of a semi-circular cam in our invention providessignificantly improved tension control. By offsetting the geometric axisof a semi-circular cam from the shaft axis or axis of rotation, rovingpackages of greater average density and therefore of increased weightand yardage can be produced. For ofiset adjustments we have used a drivescrew such as that shown at FIG. 4, with 40 threads per inch. Thus oneturn of the thumb nut 44 moves slide 37 and cam axis .025".

With the cam axis offset, as the cam is rotated by step movements of therack through successive equal angular displacements, camming surfacearcs of increasingly greater length are rotated past a reference planepositioned vertically through the axis of rotation. Thus the lengths ofcable wound on the cam and the lengths of belt shipper stepmovements aresuccessively of greater magnitude.

Of course a cam having a camming surface of circular arc contour is byno means the only type of cam which can be used. Other curved cammingsurfaces can be devised for accommodating particular roving frames androving winding conditions. A basic criterion for the cam is that thecontour of the curved camming surface shall have radius of curvaturewhich, in a reference system of polar co-ordinates where the polecoincides with the geometric axis of the cam, is of increasingly greaterlength as the radius is rotated through successive equal angles aboutthe pole. Then with the added facility of the cam center adjustmentassembly 31 very precise, automatic tension control can be provided foreach layer of roving.

With the apparatus of this invention, the belt shipper step movementscan be provided in the conventional manner when a circular arc type camis used Without offset. The belt shipper movements can be varied by theuse of special cam profiles and by adjusting the offset distance betweenthe cam geometric axis and the axis of rotation. The cam profile can betailored or custom-made for unusual winding requirements or toaccommodate special or unusual roving frames, worn cone drives or conesof special design.

In the embodiment of FIG. 2, the tension regulator apparatus of theinvention is shown installed for use with the conventional mechanism ofa 10" x S" Saco-Lowell F.S.. 2 roving frame where we have used thefollowing with good results: cam diameter of 19.098"; off-set centeradjustability of from 0 to 1% and a sector gear 29 with 19.400 O.D., 10pitch, 192 teeth. The invention can as well be installed, for example,in a Whitin roving frame where the rack and belt shipper movements arethe same, the principal difference for the purposes of this inventionbeing only in the arrangement of the tension gears for driving the rack.The invention has been used in a 12" X 6 Whitin roving frame with theresult that standard roving bobbin weight of 50 ounces has beenincreased to 5 8 ounces, representing an increase in weight of 14% ineach package of roving. This increase has been obtained without causingmore than the usual and normal number of tension breaks or overrunsencountered in producing mills.

An alternative embodiment of our invention is shown in FIG. 5 installedfor tension control in a conventional Whitin roving frame. Most of theconventional components of the roving frame in FIG. 5 are similar tothose which were described in connection with FIG. 1. For ease ofreference, identical components in FIGS. 1, 2 and 5 bear the sameidentifying numerals. The principal distinction to be noted is thattumbler shaft 12 carries a spur gear 49 instead of a worm gear (shown at22 in FIG. 1) for driving the tension gears. As before, the tensiongears are used in this embodiment for providing successive equal angulardisplacements of a cam upon each successive tumbler shaft halfrevolution. Tension gears 50 and 51 can be changed so that the tensiongear ratio may be varied from time to time to change the magnitude ofthe angular cam displacements.

In this embodiment, cam 52 is mounted for counterclockwise rotation oncam shaft 53. The cam 52 is also positioned on shaft 53 by an off centeradjustment assembly 31. In this embodiment, gear 51, which is the lastelement of the tension gear train, drives an actuating shaft 54 which isthe input member of gear box 55. The output member of gear box 55 is thepreviously mentioned cam shaft 53. This may best be seen in FIG. 6.

According to this embodiment, the rack 11 remains affixed to the beltshipper 21. A cable 32 is attached as before to the camming surface edgeof cam 52. This cable passes around sheaves 56 and 57 mounted in theroving frame, and the outer end of the cable is clamped at 58 to the endof the rack 11.

The operation in this embodiment is as follows. When tumbler shaft 12 isrotated through successive half revolutions upon completion of eachlayer of roving on the bobbins, the tension gears, actuated by spur gear4? on the tumbler shaft, are displaced through successive equal angularincrements. Thus the actuating shaft 54 and the cam shaft 53, which areconnected through the gear box 55, are also rotated through equalsuccessive angular increments for driving the cam. In this case, cam 52is rotated in the counter-clockwise direction through successive equalangles.

With the cam adjusted for off-set center rotation by assembly 31, theamount of cable which is wound on the camming surface increases witheach displacement of the cam. The cable and rack, and thus the beltshipper to which the pack is connected, are longitudinally displaced insuccessively greater increments. The belt shipper step movements, asbefore, control bobbin rotating speed and roving tension.

Specifically for the 12" x 6" Whitin frame mentioned, we have used thefollowing with good results: ratio across the gear box 55, 10:1; tensiongears of from 30 to 50 teeth; offset center distance adjustability offrom 0" to 1%" and a cam diameter of 19.098".

In the remaining components shown and numbered in FIGS. 5, 6 and 7, butnot as yet explained, winding shaft 59 is provided for resetting theloving frame.

Winding shaft 59 is mounted in the roving frame connected at its lowerend by a series of spur and wheel gears to the rack '11. As the rack isdisplaced in response to angular cam movements, the winding shaft 59 andthe hand wheel 60 affixed at the upper end of the winding shaft, areslowly turned. At the end of the doff, in order to reset the rovingframe for the next run, the tension gears are thrown out of mesh, thebottom cone 20 is raised to clear the drive belt 18 and the windingwheel 60 is manually turned backwards. Thus the winding shaft 59 drivesthe rack 11 and the belt shipper 21 to the starting position so thatbelt 18 is returned to the large end of the power cone 19.

It should be noted, of course, that other means can be incorporated fortransmitting the successive step movements, which have been described,to and from the cam and follower. As an illustration of that which iswithin the skill of the art, the cam and follower can be arranged asintermediate members of a gear train. A properly designed gear trainwould thus permit use of a cam which has smaller physical size than thatpreviously described. This in turn would provide for greater flexibilityin locating and mounting the tension control mechanism in a particularframe.

In the foregoing specification, we have described our invention indetail. For ease of understanding we have referred in our description topresently preferred and to alternative embodiments. Of course, manyvariations of these embodiments will occur to those skilled in the art.Accordingly, we do not propose to be limited to the details which havebeen set forth. Our invention is defined in the following claims.

We claim:

1. In a roving frame having rotatable bobbins on which roving packagesare wound, the bobbins being mounted on a member of the frame forreciprocatory movement, means for variably controlling roving tensionwhich means comprises a cam having an edge camming surface, a camfollower, said follower being mounted in said frame against said cammingsurface, said follower being movable with respect to said surface, saidcamming surface having a contour which is prescribed in terms of cammingand reference dimensions of the cam wherein, in a reference system ofco-ordinates, the reference dimension is an independent variable and thecamming dimension is a dependent variable, which dependent variableincreases through successively increasing increments as said independentvariable increases through successively equal increments, and meansconnected to a tension gear mechanism in said frame and adapted to drivesaid cam and said follower relatively to cause said follower to changeits position with respect to said cam whereby said follower is displacedby successively in creasing increments, said follower being connected insaid frame to a frame mechanism which controls the rotating speed of thebobbins, changes in the position of said follower being adapted toactuate said frame mechanism.

2. In a roving frame having rotatable bobbins on which roving packagesare wound, the bobbins being mounted on a member of the frame forreciprocatory movement, means including a tumbler shaft for reversingthe direction of reciprocatory movement of said member upon completionof each layer of roving on the bobbins, gear mechanism driven by saidreversing means in successive equal increments upon said completion ofeach layer, a pair of belt pulleys and a belt-shipper mounted on amember of the frame for movement longitudinally of said pulleys, theimprovement which comprises a fiat cam having an edge camming surface, acam follower, said follower being mounted in said frame against saidcamming surface, said follower being movable with respect to saidsurface, said camming surface having a contour which is prescribed interms of reference and camming dimensions of the cam wherein, in areference system of co-ordinates, the reference dimension is anindependent variable and the camming dimension is a dependent variable,which camming dimension increases in successively increasing incrementsas said reference dimension increases in equal successive increments,means connected to said gear mechanism and adapted to drive said cam andsaid follower relatively and thereby displace said follower bysuccessively increasing increments and means connecting said follower tosaid belt shipper whereby the position of said follower is adapted todetermine positions of said belt shipper.

3. The roving frame combination of claim 2 and in which said camcomprises a rotatable flat disc cam, said cam being mounted in saidframe on a shaft for rotation about an axis.

4. The roving frame combination of claim 3 and in which said followercomprises a flexible cable, one end of said cable being connected tosaid cam, said cable being wound on said camming surface by rotation ofsaid cam.

5. The roving frame combination of claim 4 in which the other end ofsaid cable is connected to said belt shipper whereby said belt shipperis displaced longitudinally of said belt pulleys in successivelyincreasing increments when said follower is displaced.

6. The roving frame combination of claim 5 and in which said meansconnected to said gear mechanism comprises a rack extension and arotatable wheel gear, said wheel gear being mounted on said shaft andengaging said extension.

7. The roving frame combination of claim 3 and in which said cam issupported on said shaft by means whereby the distance between thegeometric axis of said cam and the axis of rotation of said shaft isadjustable.

8. The roving frame combination of claim 4 and in which one end of arack member of said gear mechanism is connected to the other end of saidcable, said one end being opposite the end of said rack which isconnected to the belt shipper, and pulleys mounted in said frame onwhich said cable is guided.

9. The roving frame combination of claim 8 and in which said meansconnected to said gear mechanism comprises gear means connected to saidshaft and engaging a tension gear member of said mechanism.

10. In a roving frame having rotatable bobbins on which packages ofroving are wound, the bobbins being mounted on a member of the frame forreciprocatory movement, means including a tumbler shaft for reversingthe direction of reciprocatory movement of said member upon completionof each layer of roving on the bobbins, gear mechanism, including arack, driven by said tumbler shaft in successive equal increments uponsaid completion of each layer, a pair of belt pulleys and a belt shipperadapted for movement longitudinally of said pulleys for changing thebobbin rotating speed, one end of said rack being connected to said beltshipper, the improvement which comprises a rotatable flat cam having acurved edge camming surface, said cam being supported in said frame on ashaft for rotation about an axis, means connected between said cam andsaid shaft and adapted for changing the distance between the geometricaxis of said cam and its axis of rotation, a cable type cam followeradapted to be wound on said camming surface, one end of said cable beingattached to said cam, the other end of said cable being connected to theother end of said rack, said camming surface having a prescribedcontour, said contour having a radius of curvature which, in a referencesystem of polar coordinates where the pole coincides with the geometricaxis of said cam and the initial line coincides with the shortest radiusof said cam, increases in length in successively increasing incrementsas said radius is rotated by equal angular increments about said pole, arack extension and a wheel gear, said wheel gear being mounted on saidshaft and engaging said extension for angular displacement of said camin successive equal increments upon said complelion. Of each layer,whereby successively increasing 13 amounts of said cable are wound onsaid camming surface.

11. In a roving frame having rotatable bobbins on which packages ofroving are wound, the bobbins being mounted on a member of the frame forreciprocatory movement, means including a tumbler shaft for reversingthe direction of reciprocatory movement of said member upon completionof each layer of roving on the bobbins, gear mechanism, includingtension gears, driven by said tumbler shaft in successive equalincrements upon said completion of each layer, a pair of belt pulleysand a belt shipper adapted for movement longitudinally of said pulleysfor changing the bobbin rotating speed, the improvement which comprisesa rotatable'flat cam having a curved edge camming surface, said cambeing supported in said frame on a shaft for rotation about an axis,means connected between said cam and said shaft and adapted for changingthe distance between the geometric axis of said cam and its axis ofrotation, a cable type cam follower adapted to be wound on said camrningsurface, one end of said cable being attached to said cam, the other endof said cable being connected to said belt shipper, a tension linkageconnected between a structural member of said frame and said beltshipper, said camming surface being of prescribed contour, said contourhaving a radius of curvature which, in a reference system of polarcoordinates where the pole coincides with the geometric axis of said camand the initial line coincides with shortest radius of said cam,increases in length in successively increasing increments as said radiusis rotated by equal angular increments about said pole, and gear meansconnected between said tension gears and said shaft for angulardisplacement of said cam in successive equal increments upon saidcompletion of each layer, whereby successively increasing amounts ofsaid cable are wound on said camming surface.

References Cited in the file of this patent UNITED STATES PATENTS2,870,597 Hill Ian. 27, 1959 2,898,729 Anderson Aug. 11, 1959 2,901,882Granberry Sept. 1, 1959

